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Biomedical subjects

C D Bracewell

Publications and source records attributed to C D Bracewell.

At least 19 recordsLinked to original sources
PubMed1989

Serological and bacteriological investigations of chickens from flocks naturally infected with Salmonella enteritidis.

Groups of 10 birds were obtained from four flocks which had shown evidence of natural salmonella infection. S enteritidis had been isolated from three flocks and S typhimurium from the fourth. Each bird was housed in a separate cage and blood samples and cloacal swabs were taken weekly to follow the course of natural infection. After four weeks the birds were killed and examined post mortem. The isolation of Salmonella species could not be related to the serological results. In individual birds the rapid slide test and tube agglutination test could not be relied upon to detect infection; the microantiglobulin test and the enzyme-linked immunosorbent assay (ELISA) were more sensitive than the other tests and detected some infected birds that were negative by the rapid slide and tube agglutination tests, and also showed high titres in some birds from which Salmonella species could not be isolated post mortem. Sera obtained from two flocks which had a history of natural S enteritidis infection were evaluated by all the tests; evidence of infection was found with the microantiglobulin and ELISA tests but not with the other tests.

Agglutination Tests↗
PubMed1986

Chlamydiosis in birds in Great Britain. 1. Serological reactions to chlamydia in birds sampled between 1974 and 1983.

A total of 6593 serum samples from birds, received for diagnostic testing or surveys between 1974 and 1983, were titrated by direct complement fixation (CF) test against Chlamydia psittaci antigen. The percentage of positive reactions found was variable for domestic poultry, ranging from 1.5 in chickens to 22.2 in geese, and was highest in pigeons Columba livia (47.3) and collared doves Streptopelia decaocto (51.4). A moderate incidence was found for game birds (29.0), wild ducks (23.3) and imported birds of the order Psittaciformes (15.9). The highest titres were found in pigeons, collared doves and psittacines, confirming that infection is both frequent and active in these birds in Britain. Results of isolation of chlamydia from similar sources will be reported subsequently.

Animals↗
PubMed1986

Chlamydiosis in birds in Great Britain. 2. Isolations of Chlamydia psittaci from birds sampled between 1976 and 1984.

A total of 1531 diagnostic submissions from birds were examined by culture for the presence of Chlamydia psittaci between June 1976 and December 1984 by growth in NCTC 929 clone L mouse fibroblast cells, pretreated with an inhibitor of cell division, followed by direct immunofluorescence microscopy. Of these, 196 were found positive. The continued importance of psittacine birds as potential sources of infection was shown by the high number of positives (139) obtained from birds of that order. The percentage of submissions found positive was highest in parakeets (30.1) and was fairly high in psittacines as a group (16.6), but the latter figure was exceeded by the group of collared doves (Streptopelia decaocto) and wood pigeons (Columba palumbus) (25.0). Domestic poultry generally gave low rates, turkeys being the highest. Both the numbers of submissions and their rates of positives increased between 1980 and 1984. Comparing the isolation rates from the various organs sampled, the intestines gave the highest rate (20.4 per cent positive), closely followed by the other internal sites. The superficial swabbed sites (eye, nasal cavity, cloaca) gave lower rates.

Animals↗
PubMed1983

Cell mediated and humoral immune response of chickens to inactivated oil-emulsion infectious bronchitis vaccine.

A lymphocyte transformation microassay was used to study cell mediated immunity (CMI) in chickens following primary and secondary vaccination with inactivated oil emulsion infectious bronchitis (IB) vaccine and subsequent challenge with Massachusetts-41 (M-41). Humoral immunity was monitored for comparison, using the haemagglutination inhibition (HI) microassay. Positive stimulation indices (2 to 2.7 after primary and 2 to 4.8 after secondary vaccination) were lower and HI titres were higher than those previously reported following primary and secondary vaccination with live IB vaccines. The highest HI titres appeared in birds which had received the inactivated vaccine as a secondary vaccination. Challenge of vaccinated and revaccinated birds resulted in strong HI and weak CMI secondary responses. There was no correlation between CMI and HI antibody production. Monitoring egg production and clinical signs showed that a high level of protection against challenge resulted from revaccination with an inactivated oil adjuvant vaccine.

Animals↗
PubMed1982

Chlamydia infection in ducks: preliminary communication.

Chlamydia psittaci was isolated from cloacal swab pools from ducks in processing plants, and from cloacal and conjunctival swab pools from ducks on farms, in a small proportion of the samples examined. These isolates were difficult to passage. This difficulty was partly overcome by the use of emetine as the cell growth inhibitor. The direct complement fixation (CF) test was modified for testing duck sera by using complement at the los dose of 1.5 units. By this method, positive titres were demonstrated in experimentally prepared duck antisera, and in some of the samples collected from breeding and fattening ducks.

Animals↗
PubMed1981

Characterisation of Brucella abortus strain 19 cultures isolated from vaccinated cattle.

Thirty-four cultures recovered from material of bovine origin in England, Scotland and Wales were identified unequivocally as Brucella abortus strain 19 (S19). All had the properties of carbon dioxide-independent B abortus biotype 1 strains, were inhibited by penicillin G and thionin blue at standard concentrations and behaved in oxidative metabolism and guinea pig virulence tests as typical S19. Their sensitivity to i-erythritol varied somewhat between cultures as did reference subcultures of S19. Of the total number of isolates, 11 were recovered from abortion material or cyetic products, 10 were from calves which died from a hypersensitivity reaction within 24 hours of S19 vaccination and the remainder were from milk or internal organs. From the evidence available, there is little to suggest that calfhood vaccination with S19 has resulted in persistent systemic infection in other than a very small proportion of the animals inoculated.

Animals↗
PubMed1981

Immune responses of breeding chickens to trivalent oil emulsion vaccines: responses to infectious bronchitis.

Three similar flocks of broiler breeder parent chickens that had been given live infections bronchitis (IB) vaccines during rearing were injected at 20 weeks of age with three different oil emulsion vaccines: a commercial monovalent Newcastle disease (ND) vaccine (flock A); an experimental bivalent vaccine containing ND and infectious bursal disease (IBD) components (flock B); and an experimental trivalent vaccine containing ND, IBD and IB components (flock C). One week after vaccination 40 hens from flock A and 40 from flock C were taken to the laboratory and their egg yields individually recorded. At 37 weeks of age they were challenged by aerosol exposure to virulent IB virus. The egg production dropped significantly in the hens from flock A but not in the hens from flock C. On the farm, flock C showed a higher mean IB virus antibody titre four weeks after vaccination but titres rose in all three flocks indicating the presence of active IB virus infection. No differences in egg yields were found between the three farm flocks.

Animals↗
PubMed1981

Cell mediated and humoral immune response of chickens to live infectious bronchitis vaccines.

A lymphocyte transformation microassay was used to study cell-mediated immune (CMI) responses in chickens following inoculation with live infectious bronchitis virus vaccines H 120 and H 52 and challenge with Massachusetts-41 (M-41). Humoral immunity was monitored for comparison, using haemagglutination inhibition (HI) microassay. Specific stimulation of infectious bronchitis virus sensitised lymphocytes was demonstrated by their lack of response to Mycoplasma synoviae and Newcastle disease virus antigens. Positive infectious bronchitis virus stimulation indices appeared before HI titres and ranged from 2.0 to 7.1 over a period of five to 33 days after primary vaccination with H 120. Revaccination with H 52 produced a strong secondary HI response and a relatively weak CMI response. Challenge of vaccinated and revaccinated birds also resulted in strong HI and weaker CMI secondary responses but the more pronounced CMI responses were in the revaccinated-challenged group. There was no correlation between CMI and HI antibody production but a negative correlation was demonstrated between peak CMI responses after vaccination and severity of clinical symptoms after subsequent challenge.

Animals↗
PubMed1980

An association between arthritis and persistent serological reactions to Brucella abortus in cattle from apparently brucellosis-free herds.

Twenty-four cases of stifle (femoro-tibial joint) arthritis, in Friesian heifers that had failed their first blood test for brucellosis, were examined pathologically and by serological and cultural tests for brucella. The arthritis was confined to the stifle and was non-purulent. The cases showed several other similar features, including evidence of trauma, erosions of articular surfaces, synovial proliferations and granulomata containing germinal centres and plasma cells. The synovial fluid was turbid, discoloured and usually increased in volume, with high antibody titres to brucella. Cultures were invariably negative for brucella, but examinations of cryostat sections stained by fluorescent antibody against B abortus were positive in five out of six cases examined some showing particles with a morphology resembling that of brucella.

Animals↗
PubMed1980

Experimental infection of turkeys with egg drop syndrome 1976 virus and studies on the application of the haemagglutination inhibition test.

Evidence that turkeys can be infected with virus 127 by the combined intranasal and oral route and that the haemagglutination inhibition (HI) test can be used to demonstrate past infection is presented. Experimental infection of turkeys (six weeks old and six months old) with virus 127 did not result in any clinical signs. However, a rapid HI response was detectable one week later and detectable titres were found 28 weeks after infection. No antibody was detected in 392 sera examined from commercial turkey flocks.

Animals↗